Hispanics are the largest and fastest growing minority group in Arizona, comprising 16.2% (1980 Census) of the State's population. In arizona, 90% of the Hispanic population is of Mexican heritage. They are a young population: fifty-seven percent of all Mexican- Americans are under 25 years of age compared with thirty-eight percent of white non-Hispanics in Arizona. Despite their rapid growth (and the implications of that growth for maternal and child health services) and increased interest in their health by policy makers, politicians, and others, large gaps in our understanding of their health status, use of health services, and unmet health care needs remain. Studies in recent years indicate that Mexican-American women are less likely to seek prenatal care in the critical first trimester of pregnancy and to average fewer prenatal visits than white non- Hispanic women. Mexican-American children also average fewer physician visits per year than non-Hispanic children. A number of studies provide convincing evidence that perinatal and infant care services are beneficial and that use of services by these groups is associated with improved health outcomes. This study will investigate the use of health services of 310 Mexican-Americans and 310 White non-Hispanic infant enrolled in the Arizona Health Care Cost Containment System (AHCCCS), an HMO- oriented Medicaid demonstration project, during their fist year of life. The use perinatal services by their mothers will also be explored. The dependent variables include the number of immunizations and other preventive care services by the infants, use of care during the first trimester of pregnancy, total number of prenatal visits and use of post partum services. The study will identify socio-economic and organization as well as cultural factors, (specifically the level of acculturation, health beliefs about benefit of specific preventive health services and role of the family), associated with the use of health services in an HMO setting where financial barriers have been removed or reduced. The study will compare use of these services by Hispanics and non- Hispanics and attempt to explain differences. The Investigation will be conducted as a descriptive analytic study using data collected from medical records and a household interview. Based on empirical finding, suggestions will be made for changes in policies or programs to eliminate differences in use.